| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply of simple circuitry capable of detecting the period when energy is supplied from the primary to the secondary of a transformer accurately. SOLUTION: A first switching element Q1 and a second switching element Q2 are connected in series between the output ends of a full-wave rectifier circuit 2 for rectifying the AC voltage of an AC power supply 1, and a current resonance capacitor Cri, a resonance reactor Lr and the primary winding P1 of a resonance transformer T are connected in series across the first switching element Q1. Furthermore, a circuit D<SB>0</SB>, 14 for rectifying and smoothing the voltage of the secondary winding S, a control circuit 11 for turning the first switching element and the second switching element on/off alternately based on the output voltage from the rectifying/smoothing circuit, and a circuit 12 for detecting the period when energy is delivered from the primary to the secondary based on the voltage of an auxiliary winding P2 coupled tightly with the secondary winding S and outputting a resonance period detection signal are provided. COPYRIGHT: (C)2006,JPO&NCIPI
|
